The present invention relates to a film exposure apparatus.
Heretofore, in film exposure apparatuses, a frame holding a mask body, such as a mask film or mask glass, has been disposed so as to be movable up and down relative to another frame holding a flat plate body having photosensitive material applied thereto or spreaded thereon (hereinafter simply referred to "photosensitive flat plate body"). The frame holding the mask body is moved up and down relative to the frame holding the photosensitive flat plate body to place the mask body on the flat plate body, and the air between these bodies is evacuated so that they come into close contact with each other before exposure operation.
Because the flat body and the mask body are held by their respective frames and because they are so constructed that when these bodies are in contact with each other the mask bears against the flat plate body, if the thickness of the flat plate body is uniform, then no problem arises even when a conventional exposure apparatus is used.
However, the thickness of photosensitive flat body is not always uniform. For example, in a case where a cross section of a photosensitive flat plate body takes a trapezoidal form and tapers off toward its one side, even if a frame holding the flat body and a frame holding a mask body are in contact with each other, the mask body is not totally in contact with the whole opposed surface of the flat plate body in a conventional exposure apparatus. Therefore, an undesirable space exists locally between the opposed surfaces of the bodies. When such a situation occurs, a certain pattern drawn on the mask body lying on or below the space is not precisely projected on the flat plate body, whereby accurate exposure of mask pattern cannot be obtained. This is a serious disadvantage.
In view of the foregoing, it is the object of the present invention to provide an exposure apparatus which has a simple construction and is free from the aforementioned disadvantage.
This object is achieved, in accordance with the present invention, by holding a frame that holds a mask body such that the frame can rotate about at least one imaginary straight line passing through the center point of the held mask body.